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The Role of Photoperiod, Light Intensity, and Iron Concentration on Cellular Physiology Photophysiology, and Proteomics in Southern Ocean Phytoplankton

Primary production in the Southern Ocean (SO) plays a critical role in regulating the global carbon cycle, yet the physiological mechanisms governing phytoplankton responses to ir

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Primary production in the Southern Ocean (SO) plays a critical role in regulating the global carbon cycle, yet the physiological mechanisms governing phytoplankton responses to iron (Fe) limitation and variable light remain poorly constrained. Using a custom made incubation system that simulated natural diel solar variability, we examined the interactive effects of Fe availability, light intensity, and photoperiod (continuous vs. variable) on three ecologically important SO phytoplankton: Fragilariopsis cylindrus, Phaeocystis antarctica, and Thalassiosira antarctica. Physiological, photophysiological, and proteomic measurements revealed that Fe availability was the dominant factor regulating growth, carbon production, photosynthetic performance and protein expression across all species. Distinct acclimation strategies emerged: F. cylindrus exhibited marked trade-offs between productivity and photoprotection under Fe stress, consistent with adaptation to stable, low-light, Fe-poor environments; P. antarctica maintained growth by flexibly modulating photoprotective and photosynthetic capacity, reflecting high plasticity suited to dynamic, open-ocean conditions; and T. antarctica expressed a balanced strategy, sustaining productivity and photoprotection simultaneously, characteristic of coastal bloom formers with higher Fe demand. Dynamic light regimes produced smaller, species-specific effects, influencing chlorophyll content and carbon storage primarily in T. antarctica.

Clinical Editorial

bioRxiv (Biomedical Preprints) published a clinical update in Research Highlights on 09 Jul 2026. The item focuses on The Role of Photoperiod, Light Intensity, and Iron Concentration on Cellular Physiology Photophysiology, and Proteomics in Southern Ocean Phytoplankton. Review the original article for the full source wording and details.

Original source: https://www.biorxiv.org/content/10.64898/2026.07.08.736821v1?rss=1